1. Field of the Invention
The present invention relates to an electron beam-generating device for emitting an electron beam in accordance with an information signal. The present invention also relates to an image-forming apparatus and a recording apparatus employing the electron beam-generating device.
2. Related Background Art
Thin type image displaying apparatuses are known. The known thin displaying apparatus has a plurality of electron-emitting elements and an image-forming member counterposed thereto: the image-forming member being a member which emits light, changes its colors, become electrified, or deteriorates on collision of electrons, and being made of a material such as a fluorescent material and a resist material. FIGS. 92 and 93 illustrate schematically conventional electron beam displaying apparatus respectively as examples of such image-displaying apparatuses.
FIG. 92 illustrates an electron-beam display apparatus having electron-emitting elements and an image-forming member counterposed thereto, and modulation electrode provided therebetween. Specifically, the electron-beam display apparatus has a rear plate 1671, supports 1672, wiring electrodes 1673, electron-emitting portions 1674, electron passage holes 1675, modulation electrodes 1676, a glass plate 1677, a light-transmissive electrode 1678, a fluorescent material (an image-forming member) 1679, and a face plate 1680. The shadowed portions 1682 denote bright spots of the fluorescent material. The electron-emitting portions 1674 of the electron-emitting element (constituted of the parts 1672, 1673, and 1674) is formed by a thin film formation technique to take a hollow structure without contacting with the rear plate 1671. The modulation electrodes 1676 are placed in the space above the electron-emitting portions (in the electron-emitting direction) and have electron beam passage holes 1675.
With this electron beam display apparatus, thermoelectrons are emitted by heating the electron-emitting portion 1674 having a hollow structure by applying voltage to the wiring electrodes 1673; the electrons are taken out through the passage hole 1675 by applying voltage to the modulation electrode 1676 for modulating the electron beam according to an information signal; and the electrons taken out are accelerated and made to collide against the fluorescent material 1679. An image is displayed on the fluorescent material 1679, an image-forming member, by use of an XY matrix formed from the wiring electrodes 1673 and the modulation electrodes 1676.
FIG. 93 illustrates another electron-beam display apparatus which has a base plate 1791, modulation electrodes 1792, a thermoelectron beam sources (electron-emitting elements) 1793, an upward deflection electrode 1794, a downward deflection electrode 1795, a face plate 1796 having a light-transmissive electrode and a fluorescent material (an image-forming member). On the base plate 1791, the modulation electrodes 1792, electron-emitting elements 1793, and the image-forming member are placed in the named order. As shown in the broken-line circle in FIG. 93, the modulation electrodes 1792 and the electron-emitting element 1793 are placed with a spacing therebetween. The thermoelectron source is made of a tungsten wire coated with an electron-emitting substance, having the outside diameter of about 35 .mu.m, and emitting thermoelectrons at an operation temperature of from 700.degree. C. to 850.degree. C.
Conventional image display apparatuses involve problems below:
(1) In the display apparatus of FIG. 92, the modulation electrodes are placed in the space above the electron-emitting elements (in the direction of electron emission), so that the positional registration of the electron passage holes of the modulation electrodes with the electron-emitting portions is not easy, making insufficient the quantity of the electron emission of the electron beams, PA0 (2) The display apparatuses shown in FIGS. 92 and 93 have interspace between the modulation electrode and the opposing electron-emitting element. This interspace causes the following problems: (a) The distance between the modulation electrode and the electron-emitting portion cannot readily be kept constant, and the resulting variation of the distance (variation caused by impact, thermal distortion during driving, and so forth) causes undesired variation of the quantity of the electron emission of the electron beam, and (b) The distances between the modulation electrodes and the electron-emitting elements cannot readily be made uniform, and the non-uniformity of the distances causes the variation of the modulation among the electron beams emitted from electron-emitting portions.
The above problems give the disadvantages of insufficient contrast and variation of luminance of the displayed image and so forth in image display apparatuses.
To solve the above problems, the applicants disclosed, in U.S. Pat. No. 5,185,554, an electron beam-generating device which comprises an electron-emitting element and a modulation electrode for modulating an electron beam emitted from the electron-emitting element, the electron-emitting element and the modulation electrode being arranged on the same plane of a substrate, or the modulation electrode being placed on the reverse side of the substrate of the electron-emitting element, and also disclosed an image-forming apparatus employing the above electron beam-generating device.